diff --git a/CHANGELOG.md b/CHANGELOG.md
index e1d9b29c2..7ed008f9b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,11 @@
 
 ## [Unreleased]
 
+## [v0.51.201] — 2026-06-01 — Release FU (stage-batch13 — colored diff lines in tool-card snippets)
+
+### Added
+- Tool-card result snippets that contain a unified diff now render with the same green/red/cyan diff coloring already used for diffs in chat messages (reusing the existing `.diff-block` styles), with an expand/collapse toggle that preserves the coloring. Non-diff snippets are unchanged (#3336, @mysoul12138).
+
 ## [v0.51.200] — 2026-06-01 — Release FT (stage-batch12 — remote-gateway health probe + ephemeral-turn-field preservation)
 
 ### Fixed
diff --git a/tests/test_issue1824_cli_patch_diff_rendering.py b/tests/test_issue1824_cli_patch_diff_rendering.py
index c93d0281f..615281a01 100644
--- a/tests/test_issue1824_cli_patch_diff_rendering.py
+++ b/tests/test_issue1824_cli_patch_diff_rendering.py
@@ -113,6 +113,9 @@ def test_rendered_apply_patch_tool_card_html_contains_diff_lines():
         "_toolArgPreviewKeyIsHidden",
         "_formatToolArgPreview",
         "_toolCardPreviewText",
+        # #3336: buildToolCard now wraps diff snippets via these helpers.
+        "_snippetLooksLikeDiff",
+        "_colorDiffLines",
         "buildToolCard",
     ]
     functions = "\n".join(_function_source(UI_JS, name) for name in function_names)